Treesearch

Empirical models are important tools for relating field-measured biophysical variables to remote sensing data. Regression analysis has been a popular empirical method of linking these two types of data to provide continuous estimates for variables such as biomass, percent woody canopy cover, and leaf area index (LAI). Traditional methods of regression are not sufficient when resulting biophysical surfaces derived from remote sensing are subsequently used to drive ecosystem process models. Most regression analyses in remote sensing rely on a single spectral vegetation index (SVI) based on...

The coarse-scale population structure of pathogenic Armillaria (Fr.) Staude species was determined on approximately 16 100 ha Of relatively dry, mixed-conifer forest in the Blue Mountains of northeast Oregon. Sampling of recently dead or live, symptomatic conifers produced 112 isolates of Armillaria from six tree species. Armillaria species identifications done by using a polymerase chain reaction based diagnostic and diploid-diploid pairings produced identical results: 108 of the isolates were Armillaria ostoyae (Romagn.) Herink and four were North American Biological Species X (NABS X)....

This article lays out six propositions centering on a relationship between peopleplace connections and strategic behavior in natural resource politics. The first two propositions suggest a strong and direct connection between self-identity, place, and how individuals perceive and value the environment. The third, fourth, and fifth propositions tie together social group identity and place, particularly emphasizing the influence of social group identity on strategic behavior in natural resource politics. The sixth proposition relates to the geographic scale of place as a strategic choice in...

Mistletoes are aerial, hemiparasitic plants found on trees throughout the world. They have unique ecological arrangements with the host plants they parasitize and the birds that disperse their seeds. Similar in many respects to vector-borne macroparasites, mistletoes are often detrimental to their hosts, and can even kill them. Coevolution has led to resistance mechanisms in hosts and specialization by mistletoes. Birds act as "disease vectors" for the mistletoe host in a mutualistic relationship. To disperse their seeds, mistletoes attract and manipulate their avian vectors in ways that...

Calcareous fens have not been identified previously in southeast Alaska. A limited survey in southeast Alaska identified several wetlands that appear to be calcareous fens. These sites were located in low-elevation discharge zones that are below recharge zones in carbonate highlands and talus foot-slopes. Two of six surveyed sites partly met the Minnesota Department of Natural Resources water chemistry criteria for calcareous fens, with pH values of 6.7 to 7.4 and calcium concentrations of 41.8 to 51.4 mg/L but fall short with regard to specific conductivity (315 to 380 µS/cm). Alkalinity...

Heat and stable isotope tracers were used to study axial and radial water transport in relation to sapwood anatomical characteristics and internal water storage in four canopy tree species of a seasonally dry tropical forest in Panama. Anatomical characteristics of the wood and radial profiles of sap flow were measured at the base, upper trunk, and crown of a single individual of Anacardium excelsum, Ficus insipida, Schefflera morototoni, and Cordia alliodora during two consecutive dry seasons. Vessel lumen diameter and vessel density did not exhibit a consistent trend axially from the...

The goal of this simulation study was to provide information for defining thinning regimes for young Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in the Central Cascades Adaptive Management Area, located in west-central Oregon. Specifically, this study used the ZELIG.PNW (3.0) gap model to evaluate effects of experimental thinning treatments on the development of late-successional attributes and on extracted merchantable volume. Sixty-four thinning treatments were simulated for four rotation intervals (260, 180, 100, and 80 years) starting with a 40-year-old managed Douglas-fir...

The forests of the Kenai Peninsula, Alaska, underwent a major spruce beetle(Dendroctonus rufipennis (Kirby)) outbreak in the 1990s. A repeated inventory of forest resources was designed to assess the effects of the resulting widespread mortality of spruce trees, the dominant component of the Kenai forests. Downed woody materials, fuel heights, and moss depths were recorded during each inventory. Changes in downed and dead woody materials are summarized by forest type and harvest activity, compiled by fuel timelag classes. Fuel heights, fine fuels, and sound large fuels increased between...

We describe the genetic population structure of 65 bull trout (Salvelinus confluentus) populations from the northwestern United States using four microsatellite loci. The distribution of genetic variation as measured by microsatellites is consistent with previous allozyme and mitochondrial DNA analysis. There is relatively little genetic variation within populations (HS = 0.000 – 0.404, average HS = 0.186, but substantial divergence between populations (FST = 0.659). In addition, those populations that had low genetic variation for allozymes also tended to have low genetic variation at...

After a series of eight harvest treatments were completed at Hanus Bay, Alaska, on the Tongass National Forest in 1998, 27 respondents representing nine interest groups were interviewed to understand their reactions to the various harvest patterns in the eight treatment areas. Harvests patterns included three stands with 25 percent retention of basal area; three stands with 75 percent retention of basal area; a clearcut; and a full retention, or no-harvest, option. A special poster board that displayed estimates of consequences of the harvests in six areas (fish productivity, deer productiv...